For an airbag device installed on the central part of a steering device, there is an invention of the application No. 2005-168867 as filed earlier by the applicant of this application, wherein a decorative member is provided on the central part of the airbag device, and on the outer circumference thereof, an airbag cover is provided having tear-lines on the back side thereof, and a holding member for holding the airbag as folded in the airbag cover and having an opening formed for facilitating the inflation and expansion of the airbag at substantially the center thereof is contained in the airbag device.
FIG. 24 is a front view of a steering wheel provided with the airbag device that is the invention of the earlier filed application and FIG. 25 is a cross-sectional view taken along arrows I-I of FIG. 24. As shown in FIGS. 24 and 25, the airbag device MR is assembled into the central part of a steering wheel of a vehicle, and comprises a decorative member 40, an airbag 10, and an airbag cover 16. For convenience's sake, an occupant side is referred to as a front side while a side opposite from the front side is referred to as a back side in the present specification.
The airbag device MR is assembled into the central part of a steering wheel 50R of a vehicle, and comprises a decorative member 40R, an airbag 10R and an airbag cover 16R.
The airbag 10R comprises an airbag main body 10Ra and a tubular tether belt 11Ra for constraining an extension length of the airbag main body 10Ra, and the airbag 10R folded like bellows toward the occupant side is contained within the airbag cover 16R. The airbag 10R is covered with a holding member 14R in such a way as to press down a side face of the airbag 10R, on the outer circumference thereof, to thereby restrain the inflation and expansion of the airbag 10R, in the direction of the side face thereof. The main body 10Ra, and the holding member 14R are secured to a base plate 24R by a cushion ring 22R inserted into the airbag 10R. Further, the airbag cover 16R is secured to the base plate 24R in such a way as to cover up airbag 10 and such.
Meanwhile, an end of the tubular tether belt 11Ra is positioned on the rear face of a depressed part 16Ra formed on the occupant side of the airbag cover 16R, and an attachment bolt 40Ra protruding toward the back face of the decorative member 40R is secured to a connecting member 20R with a nut, thereby clamping the end of the tubular tether belt 11Ra between those members. The holding member 14R for holding the airbag 10R as folded is provided with an opening 14Rh circular in shape at the central part thereof (see FIG. 26, described later), and it is contained in the airbag cover 16R with the tubular outer circumferential part of the decorative member 40R being inserted into the opening 14Rh. The end of the connecting member 20R is clamped between the cushion ring 22R and the base plate 24R and is secured to the base plate 24R. Denoted by numeral 12′R is a gas rectification member, described in detail later.
FIG. 26 is an expansion view of the holding member 14R. The opening 14Rh for facilitating inflation and expansion of the airbag is formed at the center of the holding member 14R.
The holding member 14R is made of a woven cloth and approximate square in shape, and eight holes 14Rah, 14Rbh, to be engaged with the bolts 22Rd of the cushion ring 22R, are provided at the centers of four sides of approximate square, and at corners along diagonal lines thereof. The diameter of the opening 14Rh of the holding member 14R is larger than that of the depressed part 16Ra of the airbag cover 16R and that of the decorative member 40R and is formed to allow the folded airbag to pass through a gap defined therebetween.
FIG. 27 is a perspective view showing the state where the airbag 10R as folded is held by the holding member 14R. The central hole 11Rah is a hole of the tubular tether belt 11Ra for insertion with the bolt 40Ra, and the tubular tether belt 11Ra folded inside the opening 14Rh of the holding member 14R is held by the holding member 14R. A part of the airbag held by the periphery of the opening 14Rh of the holding member 14R is referred to as a peripheral edge part, and the part of airbag held by the outer circumference of the holding member 14R is referred to as an outer circumference part. The holding member 14R is provided to prevent the state of folding of the airbag 10R from being collapsed by holding the outer circumference part and the peripheral edge part of the airbag 10R.
When packing the folded airbag 10R by the holding member 14R, there is a case where the peripheral edge part of the airbag 10R as folded to be held by the opening 14Rh of the holding member 14R is not appropriately held by the opening 14Rh. Even in the case where the peripheral edge part of the airbag 10R is appropriately held by the opening 14Rh, there is a case where the peripheral edge part of the airbag 10R contacts the airbag cover 16R so that the airbag 10R as folded is contained in the airbag cover 16R while it is deviated from the opening 14Rh of the holding member 14R, when the airbag 10R as folded is contained in the airbag cover 16R.
If the airbag 10R is once contained in the airbag cover 16R in this state, there is a risk of exerting a harmful influence upon an expansion performance of the airbag 10R. However, since the state of holding of the holding member 14R cannot be confirmed, the airbag 10R is packed while paying attention to that the peripheral edge part of the airbag 10R is held by the opening 14Rh, thereafter the airbag 10R is accommodated in the airbag cover 16R while paying attention not to cause the peripheral edge part of the airbag 10R to contact the airbag cover 16R to be deviated from the opening 14Rh. As a result, time is taken for packing and accommodating works serving as an assembling work of the airbag 10R.
If the airbag 10R is held by the holding member 14R in such a state, the folded-state of the airbag 10R is collapsed when the inflator 30R is actuated so that the part of the airbag above the hole of the gas exhaust hole 30Ra of the inflator 30R is exponentially pushed out in the direction of expansion of the airbag, thereby rupturing tear lines provided at the rear face of the airbag cover 16R so that these airbag portions burst out largely toward the driver seat side to exert an harmful influence upon the expansion performance.
On the other hand, the airbag device has conventionally provided with a gas rectification member for rectifying the direction of flow of gas generated from the inflator and supplying flow of gas to a part of the airbag, inflating in the initial stage of expansion thereof, thereby smoothly expanding the airbag (see Patent Document 2).
FIG. 28 is a sectional view of such an airbag device. An airbag device 10P comprises a case 12P, an airbag 14P, an inflator 16P and a gas rectification member 18P wherein the airbag 14P undergoes inflation and expansion by an inflated pressure of the airbag 14P due to the actuation of the inflator 16P while the opening of the gas rectification member 18P is attached to an opening peripheral edge part 12aP of the case 12P together with the airbag 14P via a bag retainer 26P.
FIG. 29 is an exploded perspective view of the airbag device 10P. The gas rectification member 18P is disposed between the inflator 16P and the airbag 14P in the case 12P, and is expanded inside the airbag 14P due to a gas generated from the inflator 16P, and it is formed in the shape of a bag by stitching one or plural pieces of basic fabrics three dimensionally for supplying the gas from gas exhaust ports 30P, 30aP toward the interior of the airbag 14P.
The case 12P has a plurality of fixing ports 20P at the opening peripheral edge part 12aP so as to attach and secure the airbag 14P and gas rectification member 18P as shown in FIG. 28. Further, the case 12P has an insertion port 22P at the bottom side face thereof through which the inflator 16P is inserted.
When assembling, as shown in FIG. 29, a tip end 18aP of the gas rectification member 18P is inserted into the folded airbag 14P from behind. At that time, the tip end 18aP of the gas rectification member 18P is inserted into the folded airbag 14P from below, then four attachment parts 32P of the gas rectification member 18P are overlaid on corresponding attachment parts 28P of the airbag 14P from the outside.
According to the conventional airbag device 10P, the airbag 14P is folded in a state to be separated from the gas rectification member 18P, then the gas rectification member 18P is inserted into the folded airbag 14P, subsequently both the gas rectification member 18P and the airbag 14P are secured to the case 12P. When the gas rectification member 18P is inserted into the airbag 14P as folded, a space between an upper surface portion 34P and a lower surface portion 36P of the airbag 14P as folded is expanded from below so that the airbag 14P is not collapsed, and the tip end 18aP of the gas rectification member 18P is inserted into the expanded space, so that a work for supporting the airbag 14P and an operation for inserting the gas rectification member 18P are necessary to be implemented at the same time, arising a problem that the work for inserting the gas rectification member 18P in the airbag device 10P becomes troublesome.
Further, when the gas rectification member 18P is attached to the airbag device 10P, the attachment parts 32P of the gas rectification member 18P are overlaid on the attachment parts 28P of the airbag 14P from the outside while positions of the fixed holes provided in the attachment parts 28P, 32P are aligned with one another, subsequently a plurality of fixed holes 20P provided in the opening peripheral edge part 12aP of the case 12P are overlaid on the fixed holes of the attachment parts 28P, 32P while they are aligned with one another, subsequently a screw and so forth are inserted into the fixed holes to be threaded therebetween, then the gas rectification member 18P is secured thereto. Described as above, there is a problem that a work for attaching the gas rectification member 18P to the airbag device 10P is troublesome and takes time, resulting in not improving work efficiency.
Patent Document 1: JP 2005-168867
Patent Document 1: JP 2001-163143 A